We are studying the regulation of intestinal luminal enzymology by determining the effect of dietary fiber, dietary protein and bile salts on pancreatic enzyme secretion and on in vivo activation, stability and degradation of the pancreatic enzymes. Conscious rats with pancreatic and bile fistulae will be used to study these processes, so that the amount of pancreatic enzyme entering the intestine can be known for the purpose of determining the t 1/2 of inactivation of pancreatic enzymes under various conditions. The effect of dietary fiber on digestion and absorption of protein (endogenous and exogenous) and fat will be studied in rats, using tritium-labeled casein. Pancreactic enzyme secretion in response to various meals will be determined in rats with pancreatic juice collected and continuously recirculated to the intestine. These studies will be designed to determine the contribution of protein and fat to the pancreatic stimulation from a mixed meal, and to determine the effect of heat-damage on the pancreatic response to dietary protein. Chronic bile deprivation causes pancreatic enzyme insufficiency in the ileum in rats, and frequently results in intestinal obstruction. We want to determine if these two events are causally connected by determining the nature of the material obstructing the intestine and its digestibility in the presence of bile or pancreatic enzymes.